【作者】 张磊；

【导师】 杨西荣； 文志刚；

【作者基本信息】 西安建筑科技大学 ， 材料工程（专业学位）， 2019， 硕士

【摘要】 Ti-811钛合金,名义成分为Ti-8Al-1Mo-1V,是一种高铝含量的近α型耐热钛合金。它具有密度低、弹性模量高、热稳定性好、焊接性能和成型性能好等诸多优点,主要被用作要求有短程强度、长程蠕变阻力、热稳定和刚性的飞机骨架和燃气发动机零件的制造。因此,开展Ti-811钛合金薄板的研制对满足航空航天新型产品的需求和国防军工建设具有重要的意义。本文采用Ti-811合金板坯,借鉴成熟的Ti-6Al-4V包覆叠轧工艺,对其轧制参数进行优化,对其轧制过程严格控制,成功研制出1.0mmTi-811钛合金薄板。同时,本文还研究了板材在轧制过程中的组织演变,也系统研究了不同热处理制度对板材显微组织、室温力学性能以及高温力学性能影响;探讨了不同温度及应力对板材蠕变性能的影响。主要研究结果如下:通过优化轧制温度、变形量、速度等轧制参数,采用包覆叠轧工艺可生产出表面质量好、尺寸精度高、板形良好、厚度为1.0mm的Ti-811钛合金薄板,突破了冷轧工艺的生产瓶颈。板坯开坯变形从单相区开始,板材的组织由魏氏体组织逐渐转变为网篮组织,再随着二火轧制变形的增加,板材的组织开始等轴化,通过最终成品包覆叠轧后,板材的组织由等轴α、拉长α以及晶间β组成,经不同单重退火后,拉长α球化,形成了等轴组织。随着热处理温度的提高,板材的组织趋于均匀,且晶粒有长大的趋势,板材的室温强度及高温强度逐渐降低,塑性上升,其400℃高温强度可达775MPa,500℃高温强度最高可达到686MPa。板材的蠕变性能随着应力和温度的升高,开启滑移系的数量增多,塑性变形能力增强,导致蠕变性能变差,通过显微组织分析发现:蠕变的主要机理是位错滑移、交滑移。更多还原

【Abstract】 Ti-811 titanium alloy,with the nominal composition of Ti-8Al-1Mo-1V,is a near α type heat-resistant titanium alloy with high aluminum content.It has many advantages,such as low density,high modulus of elasticity,good thermal stability,good welding performance and molding performance.It is mainly used in the manufacture of aircraft frame and gas engine parts which require short-range strength,long-range creep resistance,thermal stability and rigidity.Therefore,the development of Ti-811 titanium alloy sheet is of great significance to meet the needs of new aerospace products and the construction of national defense and military industry.In this paper,the rolling parameters of Ti-811 alloy slab are optimized and the rolling process is strictly controlled by using the mature Ti-6Al-4V cladding and stacking rolling process for reference.1.0mm Ti-811 titanium alloy sheet is successfully developed.At the same time,this paper also studied the microstructure evolution of the plate in the rolling process,as well as the influence of different heat treatment systems on the microstructure,room temperature mechanical properties and high temperature mechanical properties of the plate,and discussed the influence of different temperature and stress on the creep properties of the plate.The main results are as follows:By optimizing the rolling parameters such as rolling temperature,deformation and speed,the 1.0mmTi-811 titanium alloy sheet with good surface quality,high dimensional accuracy and good shape can be produced by using the cladding and stacking rolling process,which breaks through the production bottleneck of cold rolling process.The deformation of slab start from single-phase area,and the structure of plate gradually changes from widmanstatten structure to basket structure.Then with the increase of secondary hot rolling deformation,the structure of plate begins to be equiaxed.After the final product is coated and rolled,the structure of plate is composed of equiaxed α,elongated α and intergranular β.After different single annealing,the elongated α spheroidized and formed equiaxed structure.With the increase of heat treatment temperature,the structure of the plate tends to be uniform,and the grains tend to grow.The room temperature strength and high temperature strength of the plate gradually decrease,and the plasticity increases.The high temperature strength at 400 ℃ can reach 775 mpa,and the highest high temperature strength at 500 ℃ can reach 686 MPa.With the increase of stress and temperature,the number of open slip system and plastic deformation ability of the plate increase,which leads to the poor creep performance.Through the microstructure analysis,it is found that the main mechanism of creep is dislocation slip and cross slip.更多还原